d1.setValue("C1", new Double(234.2));
d1.setValue("C2", null);
d1.setValue("C3", new Double(345.9));
d1.setValue("C4", new Double(452.7));
KeyedValuesDataset d2 = null;
try {
final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
final ObjectOutput out = new ObjectOutputStream(buffer);
out.writeObject(d1);